Mineralological Specimen

Chert (flint)

Microcrystalline quartz (SiO₂), commonly called chert; brown varieties may be termed brown flint

Botryoidal Agate

Silicon Dioxide (SiO2)

Agate

Silicon Dioxide (SiO2)

Note: No specimen visible

Iron-rich laterite or weathered ironstone

Goethite–hematite-bearing ferruginous duricrust; commonly approximated as FeO(OH) and Fe₂O₃

Likely weathered basalt

Basalt, a mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, with possible olivine and iron oxides

River Stone (Sedimentary Sandstone/Quartzite)

Arenite/Quartzite transition specimen

Mixed Rock Collection

Polylithic Geological Specimen Mix

Amphibolite

Amphibolite, composed mainly of amphibole and plagioclase feldspar

Porphyritic granite or granitic gneiss

Quartz–feldspar–biotite granite; possibly foliated into granitic gneiss

Granite

Coarse-grained felsic intrusive igneous rock, chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende

Granite (likely biotite granite)

Coarse-grained felsic plutonic rock composed mainly of quartz, alkali feldspar, plagioclase, and biotite/hornblende

Tumbled milky quartz (likely iron-stained)

Quartz — silicon dioxide (SiO₂)

Weathered granite (likely granitic river cobble)

Granite; predominantly quartz, feldspar, and mica

Tumbled blue-purple stone, possibly lepidolite or dyed quartz

Tentatively lepidolite (lithium mica; K(Li,Al)₃(Si,Al)₄O₁₀(F,OH)₂), though the photograph is insufficient for confirmation

Chert (with potential fossil inclusion)

Microcrystalline Quartz (SiO2)

Quartz-rich sandstone (likely arkosic sandstone)

Sandstone, composed mainly of quartz (SiO₂) with feldspar and minor iron-oxide cement

Tumbled gray stone, likely quartz-rich pebble

Uncertain; possibly microcrystalline quartz (chalcedony) or quartzite

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz–feldspar aggregate, possibly altered granite

Quartz pebble or seed/crumb

SiO2 (if quartz)

Echinoidea (Fossil Sea Urchin)

Echinodermata Echinoidea

Weathered vesicular limestone or calcareous tuff

Porous calcite-rich carbonate rock; composition likely predominantly CaCO₃ (calcite), with iron-oxide staining and possible silica/clay impurities

Note: Item is not a geological specimen

n/a

Blue-gray kyanite crystal

Kyanite, Al₂SiO₅

Gold Ore in Quartz

Auriferous Quartz (Au + SiO2)

Galena specimen

Galena (PbS), commonly associated with sphalerite and other sulfides

Malachite specimen

Malachite, Cu₂CO₃(OH)₂, commonly intergrown with chrysocolla and minor copper oxides

Calcite specimen

Calcite (calcium carbonate, CaCO₃), likely pale blue-green massive or cleaved calcite with iron-oxide staining

Fluorite specimen

Fluorite (calcium fluoride, CaF₂)

Calcite specimen

Calcite (calcium carbonate, CaCO₃)

Calcite specimen

Calcite (calcium carbonate, CaCO₃), likely crystalline limestone or cave-calcite aggregate

Unidentifiable Specimen

Undetermined

Chert

Microcrystalline Quartz (SiO2)

Gold in Quartz Matrix

Native Gold (Au) with Quartz (SiO2)

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide and dark-mineral inclusions

Small gray rock fragment

Undetermined; likely a common silicate-rich stone or concrete/road aggregate fragment

Botryoidal chalcedony/geode fragment

Microcrystalline quartz (SiO₂), likely quartz-lined cavity with possible calcite

Brown stone, likely a weathered chert or iron-stained rock

Unidentified brown lithic specimen; composition cannot be determined from the image

Granite with Mafic Xenolith

Intrusive Igneous Rock containing a Xenolith

Agate Geode

Cryptocrystalline Quartz (SiO2) with Chalcedony banding

Ferruginous Quartz

Silicon Dioxide (SiO2) with iron oxide inclusions (Limonite/Hematite)

Likely quartz-rich rock fragment

Indeterminate; possibly quartz-bearing granite or quartzite